Finding the Fourth Proportional to 12,786.21, 17,643.72 and 7,479.99

Step by Step Solution

1. Step 1: Write the proportion equation
   12,786.21 : 17,643.72 = 7,479.99 : x
2. Step 2: Convert to fraction form
   12,786.21/17,643.72 = 7,479.99/x
3. Step 3: Cross multiply
   12,786.21x = 17,643.72 × 7,479.99
4. Step 4: Simplify right side
   12,786.21x = 131,974,849.16
5. Step 5: Solve for x
   x = 131,974,849.16/12,786.21
6. Step 6: Final answer
   x = 10,321.66